Safety Syringe

Abstract

A safety syringe which includes an outer casing having a closed and an open end, a transition chamber having a closed and an open end, a spring assembly, and a plunger. The transition chamber is held for sliding movement within the outer casing and defines a needle concealment chamber, while the plunger defines a needle receiving chamber and is held for sliding movement within the transition chamber. A liquid medicine chamber within the transition chamber holds a precharged quantity of injectable medicine. The spring assembly is moved from its initial compressed configuration, including a needle within a needle containment chamber, when movement of the plunger and the transition chamber are moved together within the outer casing to extend the needle from a needle exit hole in the end of the outer casing. The medicine is ejected from the needle upon further movement of the plunger within the transition chamber, after which further movement of the plunger within the transition chamber retracts the needle to eject safely into the needle receiving chamber.

1 . A safety syringe comprising:
 an outer casing having a closed and an open end;   a transition chamber having a closed and an open end;   a spring assembly; and   a plunger;   the transition chamber being held for forced longitudinal movement within the outer casing and defining a needle concealment chamber formed between the closed ends of the outer casing and the transition chamber;   the plunger defining an enclosed needle receiving chamber and being held for sliding longitudinal movement within the transition chamber;   a liquid medicine chamber within the transition chamber, the transition chamber further defined between a proximal end of the plunger and the closed end of the transition chamber;   the spring assembly, being in a compressed configuration, including a needle within a needle containment chamber being supported between, the proximal closed end of the transition chamber and the closed end of the outer chamber, a distal end of the needle positioned within or immediately aligned with, but not through, a needle exist hole formed through a closed end of the outer casing;   movement of the plunger and the transition chamber together to make contact between the closed ends of the transition chamber and outer casing extending the needle from the needle exit hole;   further movement of the plunger within the transition chamber to make contact between a proximal closed end of the plunger and a proximal end of the spring assembly expels liquid medicine within the medicine chamber through and from the needle;   still further movement of the plunger within the transition chamber to make contact the closed ends of the transition chamber and the plunger retracts the needle into the needle exit hole by release of the spring assembly to an extended configuration and releases the spring assembly to eject freely into the needle receiving chamber.   
     
     
         2 . A safety syringe comprising:
 an outer casing having a closed and an open end;   a transition chamber having a closed and an open end;   a spring assembly; and   a plunger;   the transition chamber being held for forced longitudinal movement within the outer casing and defining a needle concealment chamber formed between the closed ends of the outer casing and the transition chamber;   the plunger defining an enclosed needle receiving chamber and being held for sliding longitudinal movement within the transition chamber;   a liquid medicine chamber within the transition chamber, the transition chamber further defined between a proximal end of the plunger and the closed end of the transition chamber;   the spring assembly, being initially in a compressed preloaded configuration, including a needle within a needle containment chamber being supported between, the proximal closed end of the transition chamber and the closed end of the outer chamber, a distal end of the needle positioned within or immediately aligned with, but not through, a needle exist hole formed through a closed end of the outer casing;   a first stage of movement being the positioning of the plunger and the transition chamber together into the outer casing into contact between the closed ends of the transition chamber and outer casing to extend the needle from the needle exit hole;   a second stage of movement of the plunger into the transition chamber making contact between a proximal closed end of the plunger and a proximal end of the spring assembly to expel liquid medicine within the medicine chamber through and from the needle;   subsequent movement of the plunger within the transition chamber so as to make contact the closed ends of the transition chamber and the plunger retracting the needle into the needle exit hole by release of the spring assembly to an extended configuration and releasing the spring assembly to allow the spring assembly to eject freely into the needle receiving chamber.   
     
     
         3 . A single use pre-loaded disposable safety syringe comprising:
 an outer casing having a closed and an open end;   a transition chamber having a closed and an open end;   a spring assembly; and   a plunger;   the transition chamber being held for forced longitudinal movement within the outer casing and defining a needle concealment chamber formed between the closed ends of the outer casing and the transition chamber;   the plunger defining an enclosed needle receiving chamber and being held for sliding longitudinal movement within the transition chamber;   a liquid medicine chamber within the transition chamber, the transition chamber further defined between a proximal end of the plunger and the closed end of the transition chamber;   a quantity of liquid medicine held within the liquid medicine chamber;   the spring assembly held in a compressed configuration including a needle extending within a needle containment chamber, the needle containment chamber defined by the proximal closed end of the transition chamber and the closed end of the outer chamber, a distal end of the needle positioned within or immediately aligned with, but not through, a needle exist hole formed through a closed end of the outer casing;   movement of the plunger carrying the transition chamber into the outer casing so as to make contact between the closed ends of the transition chamber and outer casing and extending the needle from the needle exit hole;   further movement of the plunger into the transition chamber so as to make contact between a proximal closed end of the plunger and a proximal end of the spring assembly expelling the liquid medicine within the medicine chamber through and from the needle;   still further movement of the plunger into the transition chamber so as to make contact the closed ends of the transition chamber and the plunger, releasing the spring assembly to an extended configuration retracting the needle back into the needle exit hole and releasing the extended spring assembly to eject freely into the needle receiving chamber.   
     
     
         4 . A method of injecting liquid medicine into a patient comprising the steps of:
 removing a safety cap from a proximal end of a safety syringe;   depressing a plunger of the syringe to a first stage of movement within an outer casing of the syringe to extend a needle into a patient from concealment within a needle concealment chamber defined between closed ends of the outer casing and a transition chamber of the syringe;   depressing the plunger to a second stage of movement into the outer casing to inject liquid medicine into the patient through the needle from a medicine chamber within the transition chamber;   depressing the plunger to a third stage of movement into the outer casing to dislodge a distal plug frictionally held within a mating seat formed into a proximal closed end of the plunger;   depressing the plunger to a fourth stage of movement into the outer casing to retract the needle back into a needle receiving chamber within the plunger;   depressing the plunger to a fifth stage of movement into the outer casing to release the needle into the needle receiving chamber and to secure the plunger from being withdrawn from the outer casing.